EP1546570B1

EP1546570B1 - Clutch protection system

Info

Publication number: EP1546570B1
Application number: EP03799038A
Authority: EP
Inventors: William Joseph Mack
Original assignee: Eaton Corp
Current assignee: Eaton Corp
Priority date: 2002-10-01
Filing date: 2003-09-29
Publication date: 2008-04-02
Anticipated expiration: 2023-09-29
Also published as: BR0314508A; WO2004031604A1; DE60320120D1; CN1695013A; DE60320120T2; US20040061603A1; JP4702595B2; AU2003263541A1; JP2006501420A; GB0309679D0; EP1546570A1; US6943676B2; CN100439739C

Description

Field of the Invention

The present invention relates to a clutch of a vehicle, and, more specifically, a system and method for protecting the clutch from excessive wear and damage.

Background of the Invention

A clutch is a mechanism designed to connect or disconnect power from one working part to another. In terms of vehicles, the clutch is used to transmit power from the motor to the drive train, and to disengage the motor and transmission when shifting gears.
In its simplest form, the clutch can be considered as comprising two plates that can be selectively placed up against one another. One plate (flywheel) is attached to and rotated by a motor. A counterpart plate (clutch plate) attaches to a system of gears that one wants to run with the power of the motor. To transfer the power of the motor to the gears, the clutch plate is pushed up against the rotating flywheel. Upon being pressed up against one another, the two plates don't initially spin in synch. Instead, the driving plate (flywheel) rotates at a faster rate than the receiving plate (clutch plate) as the receiving plate slips against the driving plate as it rotates. This spinning of the two plates at different speeds is what results in wear and damage to the clutch. However, if the two plates become fully engaged, or locked together, frictional forces are strong enough to cause the two plates to spin at the same speed and no wear occurs.
During the runnning of a vehicle, there are several operating states where the clutch fails to fully engage or disengage. Instead, the clutch "slips" excessively, resulting in premature wear and damage to the clutch. EP 0493 840 A2 discloses a vehicle clutch protection system for a friction clutch comprising a computer means to compute periodically data for the instantaneous friction performance of the clutch and to add them up in several also periodically actualized time windows stores. Associated with the individual time windows stores are respectively several limit values, the magnitude of which is i.a. a function of the air temperature of a clutch casing surrounding the clutch. Depending upon the temperature measured by means of temperature sensor and upon the limit values ruling for this temperature the computer institutes graded-protective measures. As a heat loading of the clutch increases, only the clutch comfort is increasingly reduced.
The present application has developed a clutch protector system that detects and resolves the before explained operating states, thereby reducing the amount of wear or damage subjected upon the clutch.

Summary of the Invention

The present invention relates to a vehicle clutch protection system that is the subject-matter of claim 1, and that comprises means for monitoring an operating state of a clutch, means for estimating an amount of energy dissipated by the clutch, and a control unit that compares the estimated amount of dissipated clutch energy to at least one predetermined threshold energy levels. If the estimated amount of dissipated clutch energy exceeds a predetermined threshold energy level, one or more actions is undertaken by the system to reduce the amount of energy dissipated by the clutch.

Brief Description of the Drawings

Figure 1 is a simplified illustration of a clutch protection system according to one embodiment of the present invention.
Figure 2 is a simplified flow chart depicting the basic steps taken by the clutch protection system according to one embodiment while the clutch is in an urge to move state.
Figure 3 is a simplified flow chart depicting the basic steps taken by the clutch protection system according to one embodiment while the clutch is in an engage to lockup state.
Figure 4 is a simplified flow chart depicting the basic steps taken by the clutch protection system according to one embodiment while the clutch is under severe abuse by an operator.

Description of the Preferred Embodiment

Figure 1 depicts the vehicle clutch protection system 10 according to one embodiment of the present invention. An automatic transmission 32 is selectively engaged to a motor 30 by means of clutch 20. Transmission 32 may be any type of automatic transmission typically found in a vehicle, for example, the Autoshift system made by Eaton Corporation. Additionally, transmission 32 may have the capability to be placed in a manual operating mode, thereby allowing the operator of a vehicle to determine when transmission 32 will actually shift to another gear. Motor 30 can be any type of motor used to propel a vehicle. Typically this will be an internal combustion engine, although other types of motors, such as an electric motor, may just as easily be used with the present invention. Clutch 20 is a wet clutch, which typically relies on oil not only as a lubricant but also as a coolant. A microprocessor-based control unit 40 is connected via data links 50 to motor 30, transmission 32 and clutch 20. Data links 50 may be comprised of a variety of types of data communication methods. One example of a data link 50, provided for illustrative purposes, is the J1939 link used for communication of data, such as current motor speed and torque, between a motor and a transmission system. Additionally, although only one control unit 40 is shown in Figure 1, the invention is not limited to this. For example, the system may be designed to include two controllers, such as one in the interior of a vehicle allowing for operator input, while the second is located with the transmission system for control over clutch functions.
In simple terms, the clutch protection system assess whether a vehicle clutch may be subject to possible damage, due to excessive slipping of the clutch, by calculating an estimated amount of energy dissipated by the clutch, and comparing this estimated amount of energy to one or more predetermined thresholds. Once one of these thresholds is surpassed by the estimated amount of energy being dissipated by the clutch, the system initiates one or more actions designed to place the clutch back into a safe operating state. [0012] The detailed operation of the clutch protection system according to one embodiment of the present invention will now be discussed. Based on various operating parameters, control unit 40 is able to calculate an estimated amount of energy being dissipated by clutch 20. For illustrative purposes, consider the following equations, which provide one example of how to calculate an estimated amount of energy dissipated by clutch 20 for every period of time delta T, such as, for example, every 10 milliseconds. $\begin{array}{l} Clutch Power = abs (Motor Speed - Input Shaft Speed) * net motor torque / (7426) 9950 \\ Clutch Energy = Clutch Energy + (delta T * Clutch Power - Cooling Rate) \end{array}$

Where: Speed unit is rpm
Torque unit is (1b-ft) Nm
Clutch Power unit is (BTU/sec) KW
Clutch Energy unit is (BTU) KJ
Cooling Rate = Rate at which clutch transfers energy to its surroundings
9950 (7426) = Constant based on the above units
Initially, clutch power = 0 and clutch energy is set at a predetermined default value. Subsequently, control unit 40 repeatedly calculates an estimated clutch energy, for example, every 10 milliseconds, and updates the previous values based on the most recent calculations.
The system continues to calculate and revise the estimated amount of energy dissipated by the clutch as long as the clutch is in a state that allows for excessive slippage, thereby leading to premature wear and possible damage to the clutch. This excessive slippage of the clutch is characteristic of both an i) urge to move state, and an ii) engage to lockup state. Except for transient conditions, the clutch at all other times should be in either a fully engaged or fully disengaged state, thereby precluding possible damage due to excessive slippage.
To illustrate an urge to move state, consider the following example. A driver stops his or her vehicle, engages the parking brake, and then exits while leaving the motor running. However, the driver forgets to place the transmission into neutral, thereby disengaging the clutch from the engine. As such, the running motor 30 is constantly urging the vehicle to move forward by transferring its energy through clutch 20 and the gears of transmission system 32, to ultimately cause the tires to rotate. However, as the parking brake is engaged, the tires are prevented from rolling. This prevents the gears of transmission system 32 from rotating. As a result, clutch 20 is placed in a constant state of slipping, leading to excessive wear and damage.
Similarly, clutch 20 is subject to excessive slipping when placed in a typical engage to lockup state. For example, consider an operator of a truck that is carrying a heavy load and is stopped on a steep incline. However, instead of using the brakes, the driver prevents the truck from rolling back down the hill by engaging the clutch 20 and throttling the engine 30 just enough to prevent the truck from moving. This places the clutch 20 in a constant state of slipping as it continuously attempts to engage and lockup with the engine 30.
According to the present embodiment, vehicle clutch 20 is protected from residing in an urge to move state for to long, thereby minimizing the exposure of clutch 20 to a potentially damaging operating state, by comparing the estimated amount of energy dissipated by clutch 20 to a clutch abuse threshold. See Figure 2, which depicts a simple flow chart of the steps taken by clutch protection system 10 of the current embodiment. First, control unit 40 determines whether clutch 20 is in an urge to move state 200. The system then determines whether the estimated amount of energy being dissipated by clutch 20 is above a predetermined abuse threshold level 210, indicating that there is potential for damage to the clutch 20. If the estimated amount of energy is not above the threshold level, the system ends its current line of inquiry and returns to the beginning of the routine. However, if the estimated amount of clutch energy exceeds the clutch abuse threshold 210, the protection system 10 will begin to decrease the amount of "urge to move" torque 230 generated by motor 30 and applied to clutch 20. According to the present embodiment, this decrease in torque is carried out at a constant rate, such as, for example, 15 1b-ft/sec, although other constant rates, or even variable rates, could also be readily used. This decrease in torque continues until the estimated clutch energy dissipated by clutch 20 no longer exceeds the clutch abuse threshold level 210.
Additionally, once the estimated amount of clutch energy initially exceeds the predetermined clutch abuse threshold at step 210, an optional clutch abuse counter (not shown in Figure 1) may be incremented by one in order to keep track of the number of times this situation occurs. An abuse timer (also not shown in Figure 1) may also be activated at step 220, allowing the clutch protection system 10 to keep track of the amount of time clutch 20 resides in the potentially harmful urge to move state.
Figure 3 depicts a simple flow chart depicting the steps taken by clutch protection system 10 when dealing with a vehicle whose clutch is in an engage to lockup state. Unlike the analysis performed during the urge to move state, both a clutch abuse threshold and clutch damage threshold are utilized in the process of determining what actions, if any, need to be taken to protect clutch 20 from damage. In accordance with the present embodiment, the clutch abuse threshold is lower in value than the clutch damage threshold, both of which are predetermined based on the specific type of clutch installed in the vehicle.
Control unit 40 first determines whether clutch 20 is in an engage to lockup state at step 300. In addition, it must be determined whether the acceleration pedal of the vehicle is at least partially depressed (step 302), indicating that the driver of the vehicle is currently seeking to obtain more power from motor 30 beyond that produced when in a basic idle state. If these two requirements are satisfied, it must then be determined whether the estimated amount of energy dissipated by clutch 20 exceeds a predetermined clutch abuse threshold (step 304). If any of the above steps result in a negative answer, the current inquiry process is ended and allowed to start all over. If it is determined that the estimated amount of energy dissipated by clutch 20 does exceed the clutch abuse threshold (step 304), it must be determined whether the clutch damage threshold is also exceeded (step 306).
Assuming that the estimated amount of clutch energy exceeds the clutch abuse threshold but not the higher clutch damage threshold, the inquiry process continues on with step 308. There an abuse counter is incremented, allowing the system to keep track of the number of times the clutch 20 has been placed in a potentially damaging state. The system also records, by means of a timer (not shown in Figure 1), a relative abuse time stamp for the current event, and also accumulates the amount of time the clutch spends exceeding the clutch abuse threshold but below the clutch damage threshold. A warning signal is also issued at step 310. The warning signal is directed to the operator of the vehicle, and is intended to alert the operator to the fact that he or she is abusing the clutch 20. The warning signal can be either visual, auditory, or both. One example of a warning signal, provided for illustrative purposes, is the sounding of a continuous 1 second alert followed by 1 second of silence. Furthermore, a display on the vehicle dashboard can, for example, flash a letter "C" followed by the letter "A" to indicate that a clutch abuse state is currently present.
The system 10 will continue to issue the warning signal until one of three possible conditions occurs (step 312). First, the warning signal will subside if the estimated clutch energy level falls below a clutch abuse signal-off threshold. This threshold canbe defined in numerous ways. For instance, the signal-off threshold can simply be made equal to the clutch abuse threshold. However, this can result in repeated warning signals if the average amount of energy dissipated by clutch 20 is close to the energy level that represents the clutch abuse threshold. Expected fluctuations in the clutch energy level can lead to a frequent and repeated triggering and silencing of the warning signal as the clutch energy level repeatedly exceeds the threshold by a brief amount as the energy level routinely fluctuates. To rectify this condition, the signal-off threshold level can be set at a lower level than that of the clutch abuse threshold. Accordingly, the warning signal will issue once the clutch energy level exceeds the abuse threshold, and it will not subside until the clutch energy level drops below the abuse threshold by a predetermined amount. Once subsided, the warning signal will not issue again until the clutch energy level rises enough to once again exceed the clutch abuse threshold.
The second condition that will turn off the warning signal is a change in state of clutch 20. For example, if the vehicle operator increases the speed of the motor, thereby increasing the amount of torque applied to the clutch, or alternatively, the transmission system 32 triggers a shift in gears.
The third condition that will terminate the clutch abuse warning signal is if the system, by means of control unit 40, senses that the vehicle operator has made a conscious effort to stop abusing the clutch 20. Various criteria can be used to define this condition, for example, the control unit 40 detecting a consecutive decrease in estimated clutch energy for a minimum duration of time, such as, for illustrative purposes, 100 milliseconds.
If any of the above three conditions represented by step 312 are satisfied, the warning signal is turned off at step 314. However, the clutch protection system 10 does not reset itself yet. Instead, the estimated amount of energy dissipated by clutch 20 is once again calculated and compared to the clutch abuse threshold at step 316. If the estimated clutch energy level exceeds the abuse threshold level, and continues to consecutively increase for a predetermined duration of time, the process will return to step 310 and the warning signal will once again be issued. Alternatively, if the estimated clutch energy level decreases below a clutch abuse reset threshold (step 318), for example, a predetermined amount below the clutch abuse threshold, the inquiry process is ended and the system resets.
If it is determined that clutch 20 is in an engage to lockup state (step 300), that the acceleration pedal is at least partially depressed (step 302), and the estimated clutch energy level exceeds not only the clutch abuse threshold (step 304), but also exceeds the higher clutch damage threshold (step 306), the system continues on to step 330. Similar to step 308, step 330 involves the incrementing of a clutch damage counter and the generation of a relative damage time stamp that allows the system to determine how much time clutch 20 is subject to damage.
At step 332, the control unit 40 must determine whether the transmission system 32 is under complete automatic control, or whether it has been placed in a manual mode of operation, allowing the vehicle operator to control when the transmission system 32 shifts between gears. If not in a manual shift mode, it can be determined that the clutch 20 is in a typical engage to lockup state, such as when an operator has stopped his or her truck on an incline and is using the clutch instead of the brakes to keep the truck from rolling backwards. In this instance, the control unit 40 attempts to cause clutch 20 to fully engage the motor 30, thereby preventing any more damage caused by excess slipping of the clutch 20. This is accomplished by increasing the rate at which clutch 20 engages motor 30. As the rate of clutch engagement increases, the chance of clutch damage due to slippage decreases. The end result is the full engagement of clutch 20, leading the truck or vehicle to begin to accelerate.
According to the invention, the increased rate of clutch engagement is not a constant, but instead variable depending on how much energy is being dissipated by clutch 20. The greater the amount of energy in clutch 20, the farther the clutch damage threshold is exceeded, resulting in an increased rate of damage to clutch 20. Accordingly, it would seem preferable to have clutch 20 fully engage the motor 30 as fast as possible, thereby minimizing the amount of time that clutch 20 is excessively slipping and subject to damage. However, in contrast, one would also prefer to have clutch 20 slowly engage motor 30, thereby providing more time for the operator of the vehicle or truck to react to the fact that their vehicle is beginning to accelerate.

To best satisfy both of the above requirements, a series of clutch energy ranges is established above the clutch damage threshold, with each energy range correlating to an increased rate of clutch engagement. The farther a specific energy range exceeds the predetermined clutch damage threshold level, the faster the rate of clutch engagement that is associated with that energy range. Accordingly, if a clutch energy level only mildly exceeds the clutch damage threshold, the rate of clutch engagement will increase modestly. In contrast, if the clutch energy level significantly exceeds the clutch damage threshold, rate of clutch engagement will be increased significantly as well.
For example, consider the following clutch energy ranges and associated rates of clutch engagement, provided for illustrative purposes:

Clutch Energy (BTUs) KJ	Rate ((1b- ft) Nm of Clutch Torque/sec)
Clutch damage threshold	(20) 27,1
>= Clutch energy range 1 AND	(30) 40,7
<Clutch energy range 2	(30) 40,7
>= Clutch energy range 2 AND	(45) 61,01
< Clutch energy range 3	(45) 61,01
>= Clutch energy range 3 AND	(75) 101,7
< Clutch energy range 4	(75) 101,7
>= Clutch energy range 4	(100) 155,6

Where:

Clutch energy range 1 = clutch abuse threshold + ((clutch energy maximum - clutch abuse threshold)/5)
Clutch energy range 2 = Clutch energy range I + ((clutch energy maximum - clutch abuse threshold)/5)
Clutch energy range 3 = Clutch energy range 2 + ((clutch energy maximum - clutch abuse threshold)/5)
Clutch energy range 4 = Clutch energy range 3 + ((clutch energy maximum - clutch abuse threshold)/5)
Clutch energy maximum = predetermined maximum allowable energy

While the system is increasing the rate of clutch engagement in order to prevent any further damage to the clutch 20 due to slippage, the control unit also initiates a warning signal to the vehicle operator (step 336) to alert them to the fact that the clutch is in the process of fully engaging motor 30. Similar to before, the warning signal can be any type of auditory warning, visual warning, or combination thereof, as long as it alerts the vehicle operator to the clutch engagement and provides them with time to react properly.
The warning signal continues to sound and/or display until the estimated energy being dissipated by clutch 20 drops below a damage signal-off threshold. The damage signal off threshold is established in a similar manner to that of the abuse signal-off threshold of step 312. If the clutch energy level does drop below this damage signal-off threshold, the warning signal ceases, as indicated in step 362.
Similar to the abuse reset threshold of step 318, a damage reset threshold is employed at step 364, keeping the current process active until the estimated clutch energy level drops significantly enough to end the process (step 380) and reset the system.
In another embodiment of the invention, the vehicle employing the clutch protection system of the present invention may have a transmission system that allows an operator to place it in a manual mode of operation. Thus, instead of the transmission system 32 automatically shifting gears without input from the vehicle operator, the operator controls when a shift in gears is to occur. However, a disadvantage of this manual shifting-based system is that is allows for another unique situation where clutch 20 can be placed in a damaging operating state.
In a manual shift mode, the vehicle can be driven in a manner as to place clutch 20 in another type of engage to lockup state. In this situation, however, instead of an operator trying to hold a vehicle stationary on an incline by means of the clutch 20, the vehicle is moving. Consider the following example, provided for illustrative purposes. An operator has his or her vehicle currently in a high gear and is approaching a red light. The operator begins to slow the vehicle down without disengaging the clutch 20 or downshifting the transmission system 32. Due to the slow speed, clutch 20 begins to unlock or disengage. At this point in time, the light turns green and the operator begins to accelerate their vehicle, still without shifting to a lower gear. This causes the clutch to excessively slip. Unlike the previous engage to lockup situation, one doesn't want to engage the clutch while the transmission system 32 remains in a high gear as it can cause the motor 30 to stall. The clutch protection system according to the current embodiment solves the above problem by temporarily overriding the manual shift mode and causing the transmission system 32 to automatically shift to a lower gear.
As depicted in Figure 4, if a manual shift mode of a transmission system 32 is selected (step 432), the control unit 40 determines whether the current gear the vehicle is in is the gear used to start the vehicle (step 442). This check is recessary to assure that a lower gear is available to shift down into. Assuming that the vehicle is not in one of the lower starting gears, the control unit 40 causes the transmission system 32 to down shift (step 444). At the same time, a warning signal similar to that of step 336 is initiated (step 446). Steps 360 - 380 are then repeated in the same fashion as they were carried out in the engage to lockup situation involving a transmission system 32 not placed into a manual operating mode. [0033] According to another embodiment of the present invention, the clutch protection system 10 will attempt to prevent damage to clutch 20 caused by a vehicle operator severely abusing the clutch 20. As depicted in the flow chart of Figure 5, this mode of operation requires three conditions. First, the clutch protection system 10, by means of the control unit 40, must detect the accelerator pedal being at least partially depressed (step 500), indicating that the vehicle operator is seeking increased power from motor 30. Additionally, it must also determine that a braking system of the vehicle, such as, for example, the service brakes or parking brakes, are currently engaged (step 502), indicating that the operator is accelerating and braking the vehicle at the same time. Upon meeting these two conditions, the system assesses whether the estimated amount of energy dissipated by clutch 20 exceeds the clutch damage threshold (steps 504). The system then proceeds to increase the rate of clutch engagement just as it did in step 334 of Figure 3. However, in this scenario, the rate of clutch engagement, as demonstrated in the previous table, is increased by a predetermined amount, for example, 40,7 Nm/s (30 lb-ft/sec). Thus, if the clutch energy level were between clutch energy range 2 and clutch energy range 3 of the previous table, a rate of 101,7 Nm (75 Ib-ft) of clutch torque/sec would be applied. All further steps depicted in Figure 5 are the same as those that follow step 334 of Figure 3, and will not be discussed in any further detail.
In a further embodiment of the Applicant's invention, the clutch protection system 10 is designed to provide limited functions in the event of a data link failure. For example, if the J1939 data link between the control unit 40 and motor 30 were to fail, the system will continue to estimate the amount of energy dissipated by the clutch 20, initiate warning signals when appropriate, and record abuse/damage information provided by the appropriate counters and timers. However, as the clutch protection system 10 can no longer deliver control data to motor 30, activities such as decreasing the amount of torque applied to clutch 20 will any longer be capable.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.

Claims

A clutch protection system (10), comprising:
a monitor for monitoring an operating state of a clutch (20) connecting a motor (30) to a system of gears (32);

an estimator (44) for estimating an amount of energy dissipated by said clutch;

a comparator (46) that compares said estimated amount of energy dissipated by said clutch to at least one predetermined threshold energy level; and

a control unit (40) wherein said control unit initiates one or more actions to reduce said amount of energy dissipated by said clutch when said estimated amount of energy dissipated by said clutch exceeds said predetermined threshold energy level, characterized in that the greater said estimated amount of energy dissipated by said clutch exceeds said predetermined threshold energy level, the faster said control unit performs one or more actions.
The clutch protection system according to claim 1, wherein said one or more actions initiated by said control unit comprise an issuance of a warning signal.
The clutch protection system according to claim 2, wherein said warning signal comprises a visual warning.
The clutch protection system according to claim 2, wherein said warning signal comprises an audible warning.
The clutch protection system according to claim 1, wherein said one or more actions initiated by said control unit comprise reducing an amount of torque transmitted through said clutch.
The clutch protection system according to claim 5, wherein said reduction in torque continues at a predetermined rate until said estimated amount of energy dissipated by said clutch falls below said predetermined threshold energy level.
The clutch protection system according to claim 1, wherein said one or more actions initiated by said control unit comprise increasing a rate of clutch engagement.
The clutch protection system according to claim 7, wherein an amount of said increase in rate of clutch engagement is dependent upon said estimated amount of energy dissipated by said clutch.
The clutch protection system according to claim 7, wherein said one or more actions initiated by said control unit further comprise an issuance of a warning signal.
The clutch protection system according to claim 1, wherein said one or more actions initiated by said control unit comprise automatically shifting from a higher gear to a lower gear within said system of gears.
The clutch protection system according to claim 10, wherein said shifting from said higher gear to said lower gear is prevented if said shifting would cause said motor to enter an over-speed condition.
The clutch protection system according to claim 1, further comprising a counter for recording how many times said estimated amount of energy dissipated by said clutch exceeds said predetermined threshold energy level.
The clutch protection system according to claim 1, wherein said control unit tracks an amount of time that said estimated amount of energy dissipated by said clutch exceeds said predetermined threshold energy level.
The clutch protection system according to claim 1, wherein said monitor, estimator and comparator comprise part of said control unit.
The clutch protection system according to claim 1, further comprising at least one datalink connecting said monitor to one or more sensors incorporated into said clutch.
A method of protecting a clutch mechanism (20) connecting a motor (30) to a gear system (32), comprising the steps of:
monitoring an operating state of said clutch mechanism;

estimating an amount of energy dissipated by said clutch mechanism;

determining when said estimated amount of energy dissipated by said clutch mechanism exceeds a predetermined threshold energy level; and

initiating one or more actions designed to lower said estimated amount of energy dissipated by said clutch mechanism when it is determined that said estimated amount of energy dissipated by said clutch mechanism exceeds said predetermined threshold energy level, characterized in that the greater said estimated amount of energy dissipated by said clutch exceeds said predetermined threshold energy level, the faster said one or more actions are performed.
The method according to claim 16, wherein said one or more actions include issuing a warning signal.
The method according to claim 16, wherein said one or more actions include decreasing an amount of torque applied to said clutch mechanism.
The method according to claim 18, wherein said torque is decreased at a predetermined rate until said estimated amount of energy dissipated by said clutch mechanism falls below said threshold energy level.
The method according to claim 16, wherein said one or more actions comprise increasing a rate of clutch engagement.
The method according to claim 16, wherein said one or more actions comprise automatically shifting from a higher gear to a lower gear within said gear system when said gear system is under manual control.